Automated analyzers have been developed for biochemical analysis of patient samples, such as whole blood, serum, urine, plasma and cerebral spinal fluid. Most such equipment available today is complicated to operate, large in size and high in cost.
The operation of such equipment is technically complicated. It typically requires specialized operators to be available at all times, with commensurate personnel expenses being encountered. It is usually designed for use by large laboratories serving a wide geographic area or by a large medical facility. These existing analyzers carry out tests in a defined sequence of operations designed for efficient, high volume usage.
Such large scale capacity is not always required, particularly in smaller medical clinics where large volumes of blood samples are not encountered on a daily basis. The present chemical analyzer was developed to meet the practical needs of smaller medical settings. It is designed as a desk-top unit that can be operated without specialized laboratory training. Its throughput is adequate for meeting typical clinical applications. As an example, it can be designed to produce a maximum of 164 test results per hour for routine, single reagent chemistries. To provide a representative wide number of reagents, the analyzer has been designed to have a capacity of 40 reagent containers of two different sizes on board. Its capacity can be effectively doubled by utilizing two of the chemistry instruments in tandem, both being controlled by a common workstation.
The compact nature of the analyzer can be partially attributed to the fact that a single probe arm and pipette service all of the functional liquid-handling components included within it. The common pipette is used for transferring samples and reagents, as well as for diluting liquids as needed by particular test requirements.
To obtain large volumes of tests, conventional laboratory analyzers are programmed to conduct test procedures in a fixed sequence of events. While predetermined test sequences are practical in high volume chemical analyzer applications, there is a need for more flexible operation when scaling such test procedures to meet the needs of smaller medical facilities.
The present invention provides testing flexibility by permitting random access to each cuvette on a test turntable and to each container (cups, wells and reagent bottles) on a sample/reagent tray. It is therefore not necessary for the instrument to sequence through any predetermined processing steps-the controlling software can tailor the required steps to the tests currently requisitioned. This permits a greater number of tests to be conducted while using a minimum number of containers, cuvettes and reagent bottles. The software controls the sequencing of tests based upon predetermined priority schedules, rather than defined test sequences dictated by the nature of the tests being conducted.
The automated controls for the present chemical analyzer minimize operator training and required skill levels. Sample and reagent sensing that occurs automatically during operation of the analyzer notifies the operator of depleted liquid conditions as they occur.
A unique capacitive sensing system is used for sensing liquid levels. Capacitive sensing of liquid levels is used within the chemistry instrument to maintain updated inventory information.
The use of one movable pipette to handle a variety of liquids (samples, regents and/or diluents) requires the ability to rapidly clean the pipette between each fluid delivery involving a new fluid. In addition, the pipette must be constantly checked to assure that it is properly aligned in a vertical orientation and is accurately located elevationally.
According to this disclosure, the capacitive sensing system used to monitor liquid levels in the instrument is also used in conjunction with a probe alignment module to monitor both radial and axial positioning of the pipette relative to the movable probe support. These procedures detect bent conditions prior to damage of associated equipment. Elevational alignment is critical because the pipette is used to measure liquid levels during operation of the instrument.